A sensing method of optical touch, adapted for providing and sensing a sensing beam through at least one optical sensing module, is provided. The sensing method of optical touch includes the following steps. A plurality of sensing pixel zones of the optical sensing module is selected, and a main incident angle is chosen in an incident angle range according to light intensity sensed by each of the selected sensing pixel zones, wherein the sensing beam entering the optical sensing module at the main incident angle has a maximum light intensity. Main incident angles corresponding to the unselected sensing pixel zones are computed according to the main incident angles corresponding to the selected sensing pixel zones.